When hooking up your solar battery bank, you have two options for how to connect them: in series or in parallel. The correct way to connect them will depend on many factors, including your system setup, the type of batteries you’re using, and your personal priorities for your solar power system. If you’re not sure which type of battery arrangement is right for you, consult with a solar professional. However, this article will give you a basic look at the pros and cons of connecting solar batteries in parallel.
Advantages
The primary benefit of connecting solar batteries in parallel is that it increases the available runtime of your system while maintaining the current voltage. Connecting in parallel adds the amp-hour capacities. This means that two batteries in parallel will double your runtime, three batteries will triple it, and so on. This is usually what most solar users prefer, as they want to be able to use their stored power for as long as possible whenever active solar is not available.
Another advantage of a parallel connection in your battery bank is that the entire bank is not impacted when one battery dies or has another performance-related issue. With this type of connection, when one battery dies, the remaining batteries in the bank can continue to supply power to your home. In a series connection, a dead battery impacts the entire bank, so this can be a major advantage of parallel for many users.
Disadvantages
The one major drawback of connecting your batteries in parallel instead of series is that the system voltage will be lower. When connected in series, the batteries’ volts add up instead of the amp-hour capacities, increasing the overall voltage of the storage system. However, parallel connections maintain the same, lower voltage, resulting in a higher current draw.
This means using thicker cables and experiencing more voltage drop. Larger appliances that require high voltages might operate less efficiently, or have a difficult time running off your stored power supply in a parallel connection.
Is It Right for You?
Again, whether or not a parallel connection is right for you will depend on many factors. If you want a long-running time and aren’t worried about large, high-voltage appliances, then it’s probably the best option for you. If you need to run larger equipment, a series connection might be better. Just make sure you purchase a battery that can be used in your preferred type of connection. Certain types of Victron lithium batteries can only be connected in parallel and not in series.
